The present invention relates to a stator structure, especially to a composite stator structure, wherein the winding and winding groove are separate to the stator such that the motor or generator using the stator has high efficiency, low cogging torque and low cost.
The stator winding is crucial for stator to provide high operation efficiency. The stator winding should have high electrical loading and magnetic loading to achieve high operation efficiency. To achieve high electrical loading, the stator winding should have large radius and turn number to provide high electrical loading, i.e., a large electrical current flowing in the winding. Moreover, a winding with large coil radius can reduce electrical resistance and the power dissipation according to the formula, W=I2R, wherein W is dissipated power, I is motor current, and R is coil copper resistance. Therefore, the occupying ratio of the stator winding in the winding groove should be high to allow thick coil used in the winding groove. As shown in FIGS. 12 and 12A, the best way to enhance the occupying ratio of the stator winding in the winding groove is to use winding in straight row. As shown in these Figures, the conventional inner and outer stator structure 71 comprises a plurality of stator teeth 31 with arc-shaped tooth surface 311 and tooth flank 312. The stator windings 51 are wrapped in the winding groove. The size of the opening 711 of the winding groove should be at least twice of the winding diameter such that the guiding needle of the CNC controlled winding apparatus can access the opening 711 of the winding groove to perform wrapping for the winding in straight row. Therefore, the occupying ratio of the stator winding in the winding groove is about 50% the winding in straight row. To improve the occupying ratio of the stator winding, one solution is to cut outwardly the winding groove at the center position. The cut portion has bendable connection means and the stator can be arranged in straight line to expand the opening of the winding groove. However, in above-mentioned stator, the tooth surface is wider than the tooth flank, the insulating winding groove and winding cannot be arranged on the tooth flank after the winding is achieved. The tooth flank of the stator in straight arrangement is insulated and then CNC controlled winding apparatus performs winding operation by three guiding needles. The occupying ratio of the stator winding in the winding groove is about 80% for this kind of winding. However, in above-mentioned two kinds of windings, they both need CNC controlled winding apparatus; and the winding coil passes through the needle hole of the guiding needle and wrapped by the CNC controlled winding apparatus. The above-mentioned two kinds of windings have following problems:
1. The winding apparatus is CNC controlled, the precision of winding tool is demanding and the cost is high.
2. The precise CNC controlled winding apparatus is hard to control, the cost for training and maintaining is high.
3. The torque of the CNC controlled winding apparatus is influenced by the thickness of the winding coil. A large torque will affect the structure of the hole of the guiding needle. Therefore, the precise CNC controlled winding apparatus is not suitable for winding with thick coil.
4. The winding speed is low for the CNC controlled winding apparatus (60-800 rpm), the manufacturing efficiency is low.
5. The precise CNC controlled winding apparatus has high cost (6-10 million Japanese Yan), the cost of motor thus manufactured is high.
The conventional stator has high occupying ratio of the stator winding in the winding groove and thus high efficiency. However, the conventional stator is in straight-row arrangement and requires high-cost CNC controlled winding apparatus. The present invention employs high-density silicon steel plates processed by a simple and high efficient winding machine (such as rotation winding machine) and a pressing and bending machine (such as a spring-forming apparatus) to provide a composite stator structure, whereby the motor or generator using the stator has high efficiency, low cogging torque and low cost.
In one aspect of the invention, the stator has a plurality of tooth flanks, which can be detached from the stator teeth, the largest width of the outer end of the tooth tail cannot exceed the width of the tooth flank such that the tooth tail can be embedded into the stator ring. The winding groove can be made in advance and can use simple wiring apparatus. The high-cost CNC controlled winding apparatus is saved. Moreover, the winding can be achieved in multiple axes fashion to enhance efficiency.
In another aspect of the invention, the winding can be separated formed and then assembled with the winding groove and the stator tooth. The problem of winding torque due to thick coil can be solved. When the motor or generator is used in high-pressure and low-current situation, the winding can use thinner coil. The winding can be directly wrapped on the winding groove with no distortion. The tooth tail is embedded into the embedding groove on the stator ring, thus formed a stator with high efficiency, low cogging torque and low cost.
In still another aspect of the invention, the stator teeth are separated; the tooth surface has smaller separation with adjacent tooth surface. The mouth of the winding groove is also reduced. The cogging torque of rotor is also reduced.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing, in which: